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Murine Lupus (murine + lupus)
Selected AbstractsLack of effect of a single injection of human C-reactive protein on murine lupus or nephrotoxic nephritisARTHRITIS & RHEUMATISM, Issue 1 2010Francesco Carlucci Objective It has been reported that a single dose of human C-reactive protein (CRP) can prevent and reverse the renal damage in murine models of spontaneous lupus, as well as the rapid-onset immune complex disease induced in the accelerated nephrotoxic nephritis (ANTN) model. This study was undertaken to attempt to replicate these observations using a highly purified and fully characterized human CRP preparation. Methods (NZB × NZW)F1 (NZB/NZW) mice were treated with a single 200-,g subcutaneous injection of CRP or control reagents either before disease onset at 4 months of age or when high-grade proteinuria was present at 7 months of age. Mice were monitored at least monthly for proteinuria and autoantibody levels. ANTN was induced by preimmunizing C57BL/6 mice with sheep IgG, followed 5 days later by injection of sheep anti-mouse glomerular basement membrane antibody and CRP or control reagents. Renal disease was assessed by regular urinalysis and histologic evaluation. Results CRP treatment of NZB/NZW mice, either early or late in the disease, had no effect on proteinuria, autoantibody titers, or survival. CRP administration did not reduce renal injury or alter disease in the ANTN model. Human serum amyloid P component, a pentraxin protein that is very closely related to CRP, similarly had no effect. Conclusion Our completely negative observations do not confirm that human CRP has reproducible antiinflammatory or immunomodulatory effects in these murine models, nor do they support the suggestion that CRP might be useful for therapy of lupus or immune complex,mediated nephritis. [source] A novel subpopulation of B-1 cells is enriched with autoreactivity in normal and lupus-prone miceARTHRITIS & RHEUMATISM, Issue 12 2009Xuemei Zhong Objective B-1 cells have long been suggested to play an important role in lupus. However, reports to date have been controversial regarding their pathogenic or protective roles in different animal models. We undertook this study to investigate a novel subpopulation of B-1 cells and its roles in murine lupus. Methods Lymphocyte phenotypes were assessed by flow cytometry. Autoantibody secretion was analyzed by enzyme-linked immunosorbent assay, autoantigen proteome array, and antinuclear antibody assay. Cell proliferation was measured by thymidine incorporation and 5,6-carboxyfluorescein succinimidyl ester dilution. B cell Ig isotype switching was measured by enzyme-linked immunospot assay. Results Anti,double-stranded DNA (anti-dsDNA) autoantibodies were preferentially secreted by a subpopulation of CD5+ B-1 cells that expressed programmed death ligand 2 (termed L2pB1 cells). A substantial proportion of hybridoma clones generated from L2pB1 cells reacted to dsDNA. Moreover, these clones were highly cross-reactive with other lupus-related autoantigens. L2pB1 cells were potent antigen-presenting cells and promoted Th17 cell differentiation in vitro. A dramatic increase of circulating L2pB1 cells in lupus-prone BXSB mice was correlated with elevated serum titers of anti-dsDNA antibodies. A significant number of L2pB1 cells preferentially switched to IgG1 and IgG2b when stimulated with interleukin-21. Conclusion Our findings identify a novel subpopulation of B-1 cells that is enriched for autoreactive specificities, undergoes isotype switch, manifests enhanced antigen presentation, promotes Th17 cell differentiation, and is preferentially associated with the development of lupus in a murine model. Together, these findings suggest that L2pB1 cells have the potential to initiate autoimmunity through serologic and T cell,mediated mechanisms. [source] Fc, receptor,dependent expansion of a hyperactive monocyte subset in lupus-prone miceARTHRITIS & RHEUMATISM, Issue 8 2009Marie-Laure Santiago-Raber Objective Lupus-prone BXSB mice develop monocytosis characterized by selective accumulation of the Gr-1, monocyte subset. The aim of this study was to explore the possible role of activating IgG Fc receptors (Fc,R) in the development of monocytosis and to characterize the functional phenotype of the Gr-1, subset that accumulates in lupus-prone mice bearing the NZB-type defective Fcgr2b allele for the inhibitory Fc,RIIB. Methods The development of monocytosis was analyzed in BXSB and anti-IgG2a rheumatoid factor,transgenic C57BL/6 mice deficient in activating Fc,R. Moreover, we assessed the expression levels of activating Fc,R and inhibitory Fc,RIIB on Gr-1+ and Gr-1, monocyte subsets in C57BL/6 mice bearing the C57BL/6-type or the NZB-type Fcgr2b allele. Results We observed monocytosis with expansion of the Gr-1, subset in anti-IgG2a,transgenic C57BL/6 mice expressing IgG2a, but not in those lacking IgG2a. Moreover, monocytosis barely developed in BXSB and anti-IgG2a,transgenic C57BL/6 mice deficient in activating Fc,R. The Gr-1, subset that accumulated in lupus-prone mice displayed a unique hyperactive phenotype. It expressed very low levels of inhibitory Fc,RIIB, due to the presence of the NZB-type Fcgr2b allele, but high levels of activating Fc,RIV. This was in contrast to high levels of Fc,RIIB expression and no Fc,RIV expression on the Gr-1+ subset. Conclusion Our results demonstrated a critical role of activating Fc,R in the development of monocytosis and in the expansion of a Gr-1,Fc,RIIBlowFc,RIV+ hyperactive monocyte subset in lupus-prone mice. Our findings further highlight the importance of the NZB-type Fcgr2b susceptibility allele in murine lupus, the presence of which induces increased production of hyperactive monocytes as well as dysregulated activation of autoreactive B cells. [source] Anti-DNA antibody induction of protein kinase C phosphorylation and fibronectin synthesis in human and murine lupus and the effect of mycophenolic acidARTHRITIS & RHEUMATISM, Issue 7 2009Susan Yung Objective To examine fibronectin (FN) expression in human lupus nephritis and the effect of anti-DNA antibodies on transforming growth factor ,1 (TGF,1) and FN synthesis in cultured human mesangial cells. The effects of mycophenolic acid (MPA) on this pathway, and the effects of mycophenolate mofetil (MMF) treatment in (NZB × NZW)F1/J mice were also studied. Methods Immunohistochemical analyses of renal biopsy samples from patients with active diffuse proliferative lupus nephritis were performed. Cultured human mesangial cells were incubated with human polyclonal anti-DNA antibodies, with or without MPA. (NZB × NZW)F1/J mice with active nephritis were randomized to receive either MMF (100 mg/kg/day) or vehicle treatment for 12 weeks. Results Glomerular FN expression was increased in patients with lupus nephritis, and it colocalized with IgG deposition. Anti-DNA antibodies induced protein kinase C, (PKC,), PKC,I, and PKC,II activation, increased levels of bioactive TGF,1, and increased FN synthesis in human mesangial cells (P < 0.001 for each comparison versus control conditions). Pretreatment of anti-DNA antibodies with exogenous DNA reduced their cellular binding and abrogated their induction of TGF,1 and FN synthesis. Inhibition of PKC activation in human mesangial cells prior to anti-DNA antibody stimulation had no effect on cell proliferation, but resulted in significantly reduced antibody-mediated TGF,1 secretion and FN synthesis. MPA treatment down-regulated PKC,, PKC,I, and PKC,II phosphorylation, reduced levels of TGF,1 bioactivation, and decreased FN synthesis and deposition into the extracellular matrix. MMF treatment in (NZB × NZW)F1/J mice resulted in a reduction in glomerular IgG deposition, PKC activation, and FN expression, as well as an amelioration of proteinuria. Conclusion Human polyclonal anti-DNA antibodies induce TGF,1 and FN synthesis in human mesangial cells through PKC activation, which is inhibited by MPA. [source] An orally bioavailable spleen tyrosine kinase inhibitor delays disease progression and prolongs survival in murine lupusARTHRITIS & RHEUMATISM, Issue 5 2008Frances Rena Bahjat Objective To assess whether R788, an orally bioavailable small molecule inhibitor of spleen tyrosine kinase (Syk),dependent signaling, could modulate disease in lupus-prone (NZB × NZW)F1 (NZB/NZW) mice via inhibition of Fc receptor (FcR) and B cell receptor signaling. Methods R788 was administered to NZB/NZW mice before and after disease onset. Proteinuria, blood urea nitrogen levels, and autoantibody titers were examined periodically, and overall survival and renal pathologic features were assessed following long-term treatment (24,34 weeks). The distribution and immunophenotype of various splenic T cell and B cell subpopulations were evaluated at the time of study termination. Arthus responses in NZB/NZW mice pretreated with R788 or Fc-blocking antibody (anti-CD16/32) were also examined. Results When R788 was administered prior to or after disease onset, it delayed the onset of proteinuria and azotemia, reduced renal pathology and kidney infiltrates, and significantly prolonged survival of lupus-prone NZB/NZW mice; autoantibody titers were minimally affected throughout the study. Dose-dependent reductions in the numbers of CD4+ activated T cells expressing high levels of CD44 or CD69 were apparent in spleens from R788-treated mice. Minimal effects on the numbers of naive T cells expressing CD62 ligand and total CD8+ T cells per spleen were observed following long-term drug treatment. R788 pretreatment resulted in reduced Arthus responses in NZB/NZW mice, similar to results obtained in mice pretreated with FcR-blocking antibody. Conclusion We demonstrate that a novel Syk-selective inhibitor prevents the development of renal disease and treats established murine lupus nephritis. These data suggest that Syk inhibitors may be of therapeutic benefit in human lupus and related disorders. [source] Requirement of toll-like receptor 7 for pristane-induced production of autoantibodies and development of murine lupus nephritis,ARTHRITIS & RHEUMATISM, Issue 4 2008Emina Savarese Objective The detection of high titers of antibodies against small nuclear ribonucleoproteins (snRNP) is a diagnostic finding in patients in whom systemic lupus erythematosus (SLE) is suspected. Endogenous RNA molecules within snRNP trigger Toll-like receptor 7 (TLR-7) activation in B cells and dendritic cells, leading to anti-snRNP antibody production, which is associated with the development of immune complex nephritis in SLE. The purpose of this study was to investigate the role of TLR-7 in anti-snRNP antibody production and renal disease in SLE induced by an exogenous factor in the absence of genetic predisposition, using the pristane-induced murine lupus model. Methods Serum autoantibodies, IgG isotypes, and cytokine levels in pristane-treated wild-type and TLR-7,deficient mice were analyzed by enzyme-linked immunosorbent assay. Histopathologic changes in mouse kidneys were determined by light immunofluorescence microscopy. Cell subsets in splenocytes and peritoneal lavage cells from the mice were examined by flow cytometry. Results We found that anti-snRNP antibody production induced by pristane treatment was entirely dependent on the expression of TLR-7, whereas anti,double-stranded DNA antibody production was not affected by a lack of TLR-7. Impaired anti-snRNP antibody production in TLR-7,deficient mice was paralleled by lower levels of glomerular IgG and complement deposits, as well as less severe glomerulonephritis. Conclusion TLR-7 is specifically required for the production of RNA-reactive autoantibodies and the development of glomerulonephritis in pristane-induced murine lupus, a model of environmentally triggered SLE in the absence of genetic susceptibility to autoimmunity. Specific interference with TLR-7 activation by endogenous TLR-7 ligands may therefore be a promising novel strategy for the treatment of SLE. [source] Deficiency of the type I interferon receptor protects mice from experimental lupus,ARTHRITIS & RHEUMATISM, Issue 11 2007Dina C. Nacionales Objective Systemic lupus erythematosus (SLE) is diagnosed according to a spectrum of clinical manifestations and autoantibodies associated with abnormal expression of type I interferon (IFN-I),stimulated genes (ISGs). The role of IFN-I in the pathogenesis of SLE remains uncertain, partly due to the lack of suitable animal models. The objective of this study was to examine the role of IFN-I signaling in the pathogenesis of murine lupus induced by 2,6,10,14-tetramethylpentadecane (TMPD). Methods IFN-I receptor,deficient (IFNAR,/,) 129Sv mice and wild-type (WT) 129Sv control mice were treated intraperitoneally with TMPD. The expression of ISGs was measured by real-time polymerase chain reaction. Autoantibody production was evaluated by immunofluorescence and enzyme-linked immunosorbent assay. Proteinuria and renal glomerular cellularity were measured and renal immune complexes were examined by immunofluorescence. Results Increased ISG expression was observed in the peripheral blood of TMPD-treated WT mice, but not in the peripheral blood of TMPD-treated IFNAR,/, mice. TMPD did not induce lupus-specific autoantibodies (anti-RNP, anti-Sm, anti,double-stranded DNA) in IFNAR,/, mice, whereas 129Sv controls developed these specificities. Although glomerular immune complexes were present in IFNAR,/, mice, proteinuria and glomerular hypercellularity did not develop, whereas these features of glomerulonephritis were found in the TMPD-treated WT controls. The clinical and serologic manifestations observed in TMPD-treated mice were strongly dependent on IFNAR signaling, which is consistent with the association of increased expression of ISGs with lupus-specific autoantibodies and nephritis in humans. Conclusion Similar to its proposed role in human SLE, signaling via the IFNAR is central to the pathogenesis of autoantibodies and glomerulonephritis in TMPD-induced lupus. This lupus model is the first animal model shown to recapitulate the "interferon signature" in peripheral blood. [source] Distinct mechanisms of action of anti-CD154 in early versus late treatment of murine lupus nephritisARTHRITIS & RHEUMATISM, Issue 9 2003Sergio A. Quezada Objective Treatment with anti-CD154 antibody is known to ameliorate murine lupus nephritis when given early in the disease. The aims of this study were to identify the mechanism of this early effect, to determine whether late anti-CD154 treatment could halt established nephritis, and, if so, to examine potential mechanisms of late efficacy. Methods We studied the effects of anti-CD154 treatment on autoantibody production and immune complex deposition, renal pathology, survival, and renal cytokine and chemokine messenger RNA (mRNA) expression both in (NZB × NZW)F1 mice (BW mice) and in NZM.2410 mice. Results Early treatment with anti-CD154 produced long-term survival in BW mice, with abrogation of renal immune complex deposition for months after treatment was stopped. Late anti-CD154 treatment, started after development of nephritis, could halt disease in ,40% of mice. In some mice, proteinuria could be reversed repeatedly with sequential courses of anti-CD154 antibody. The remissions induced by late treatment with anti-CD154 occurred despite ongoing renal immune complex deposition. In preliminary studies, responding mice had rapid reductions in renal mRNA for transforming growth factor ,, interleukin-10, and tumor necrosis factor ,. Conclusion Amelioration of murine lupus by anti-CD154 therapy is mediated by distinct mechanisms in early versus late intervention. We postulate that anti-CD154 therapy prevents autoantibody production and renal immune complex deposition in the early, induction phase and limits secondary tissue damage in situ in the late, effector phase. These data demonstrate that CD40,CD154 interactions are critical for the maintenance of autoimmunity and suggest a potential role for anti-CD154 as a therapeutic agent in established human lupus. [source] Enhanced susceptibility to end-organ disease in the lupus-facilitating NZW mouse strainARTHRITIS & RHEUMATISM, Issue 4 2003Chun Xie Objective Although the NZW mouse strain is phenotypically normal, fulminant lupus glomerulonephritis (GN) develops when NZW mice are bred to several other strains, such as NZB, BXSB, B6.Sle1, and B6.Yaa. Based on the observation that aging NZW mice exhibit histologic evidence of GN, we sought to test our hypothesis that NZW mice may be more susceptible to immune-mediated renal damage. Methods NZW mice, as well as C57BL/6 (B6) and BALB/c control mice, were challenged with rabbit anti,glomerular basement membrane nephrotoxic sera (NTS), to induce renal disease. The different mouse strains were monitored for the degree of clinical disease, renal pathology, chemokine profiles, and cellular infiltrates. Results Although the NZW and control strains showed similar glomerular deposits of rabbit Ig and exhibited similar levels of anti-rabbit xenogeneic immune response, the NZW mice had significantly worse pathologic changes and disease. Compared with the control strains, the NTS-injected NZW mice demonstrated significantly increased proteinuria, elevated blood urea nitrogen levels, more severe histologic GN and tubulointerstitial nephritis, increased glomerular crescent formation with macrophage and neutrophil infiltrates, elevated expression of CC and CXC chemokines (monocyte chemoattractant protein 1, RANTES, KC), and significantly accelerated mortality. Importantly, these changes occurred within a few days after NTS administration. Finally, (B6 × NZW)F1 mice were as susceptible as the NZW parents, which indicates dominant NZW contributions. Conclusion Collectively, these findings support the notion that a lupus-facilitating genome may contribute to disease susceptibility by modulating the degree of immune-mediated end-organ damage. The availability of B6-based congenic strains bearing individual NZW-derived lupus susceptibility loci will permit future genetic dissection of end-organ susceptibility in murine lupus. [source] The role of CD4+CD25+ T cells in autoantibody production in murine lupusCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2006W.-T. Hsu Summary Systemic lupus erythematosus (SLE) is a chronic, systemic autoimmune disease characterized by the loss of tolerance to self-antigen. Because it is currently not known if regulatory T (Treg) cells are involved in the pathogenesis, we determined the frequency of CD4+CD25+ T cells and assayed the related gene expression levels in CD4+CD25+ T cells isolated from both lupus mice (NZB/NZW F1) and normal control mice (DBA2/NZW F1). The results showed that the frequency of CD4+CD25+ T cells in lupus mice was lower than that of normal mice. Except for the high expression level of interleukin (IL)-10 mRNA, CD4+CD25+ T cells from lupus mice expressed normal forkhead box P3 (Foxp3) and transforming growth factor (TGF)-, mRNA, and exerted suppressive functions. Furthermore, we depleted CD25+ Treg cells of non-autoimmune mice with anti-CD25 antibody and broke their tolerance with apoptotic cell-pulsed dendritic cells for the follow-up of autoantibody levels. The mice in the CD25+ cell-depleted group had higher titres of anti-double-strand/single-strand DNA antibodies than those of the isotype control antibody-treated group. These findings indicated that CD4+CD25+ T cells might be involved in the regulatory mechanism of autoantibody production. [source] | ||||||||||